I think there is a huge miscommunication here and what are you thinking is completely different than what I was thinking. I just felt like I entered a twilight zone and go about and say "What just happened here?"
I apologize. The problem with plain-text communication like this is that occasionally the same text can be dramatically misinterpreted in tone, and apparently I took your excitement as sarcasm. Seriously, if it wasn't meant that way, I'm sorry. So I'll start over, kind of.
All I want is a hardware that hook my apple //gs to the internet via ethernet and tcp/ip. If it requires me to have 4 year degree of bachelor of apple //gs and then another 3 years to have a master to do it..then that is fine with me...I will not bother with network and just enjoy watching people do it on youtube and always ask how they did it and why I can't do it. I mean I am ok doing it this way also, really. I am fine with it.
Per my unnecessarily cranky answers above: using a MacIP router plus some sort of Ethernet to Localtalk bridge is the closest thing you can come to having an IIgs just "plugged into the network" short of one of the extremely rare Apple II ethernet cards. The downside is that it isn't a self-contained solution: you need some other widget in the mix, the specialized router, to handle the TCP/IP encapsulation/decapsulation. (The reason I interpreted your reply as sarcastic is I thought you were coming down on me for suggesting it *because* you knew that it has that external dependency and were making it clear that any solution that wasn't completely contained inside the IIgs was unacceptable.)
If you're fine with that dependency then, well, if you're looking to write native IIgs software (IE, using the GS/OS graphical user interface instead of something self-contained like Contiki) the programming interface (IE, the Marinetti TCP/IP stack) is the same. Therefore if you used this setup instead of Uthernet card to write your software your programs *should* also work for someone using an Uthernet. (Or PPP, or SLIP, or whatever other link-layer drivers the stack supports.) Using a bridge instead of Uthernet also has some non-TCP-related advantages; for instance, there is no Appleshare driver for Uthernet, which means you can't use Macintosh file sharing protocols.
The Apple IIgs and GS/OS actually has excellent Appletalk support built into it, including the ability to boot over a network, and there exists a wonderful easy-to-use software bundle to make use of it.(*) Therefore, even if you're not interested in TCP/IP at all a localtalk bridge can be really useful if you're a IIgs owner.
(* Note also: the latest versions of A2SERVER can automatically set up MacIP on Rasbian and Debian, although I can't personally vouch for it yet. So if you set up A2SERVER you might get your MacIP router for free.)
The going price for the bridges is still only about $20-$30, so even if you buy a Raspberry Pi solely to dedicate to your IIgs the cost is still less than an Uthernet card, if you can find one. Downside is you need to learn some stuff about MacIP network routing to get it going. If you think you're up for the challenge by all means go for it, don't let my mistaken crankiness discourage you. Again, many apologies.
(When I get some free time I'm intending to fire my IIgs up again and play with it myself, but until then unfortunately I can't be a whole lot more clear on the specifics of what works and what doesn't on the IIgs end. I know I was having issues in part because a standard 1.25MB ROM 01 IIgs just doesn't have enough RAM to load all the software stacks needed for NetBoot/Appletalk *and* TCP/IP and leave enough left over to run anything useful. If you're really interested in programming TCP/IP on a IIgs you'll probably want at least 2MB of RAM.)
